1. Field of the Invention
The present invention relates to the communication of digital information, and more particularly, to methods and systems for controlling interchange of digital information using a location integrity attribute associated with the digital information.
2. Description of Related Art
Rapid advances in computer, telecommunications and networking technology have enabled an avalanche of new opportunities and applications that were impossible just a few years ago. These advances are exemplified by the explosive growth in popularity of the Internet. As known in the art, the Internet is an interconnection of computer networks that enables computers of all kinds to communicate with each other and share information. Companies, individuals, government agencies, charitable organizations, and academic centers, of all sizes, regularly use the Internet to share information, deliver services, and exchange a wide range of content. The Internet functions as a distributed network of systems that is neither controlled nor managed by any one entity. Physical and logical pathways that facilitate the exchange of information connect these networks to each other.
In spite of the tremendous value that this information access has brought to society, there are also enormous costs associated with the uncontrolled flow of information. One of the most important considerations for a communication system is the control over information security and access. In many cases, a sender of information wants to ensure that the intended recipient can only access the information, and that any other unintended recipients of the information are denied access. This information security and access control is typically provided by an encryption system that converts the information into a secret code for transmission over a public network. In an encryption system, the sender converts the original data, or “plaintext,” into a coded equivalent called “ciphertext” using an encryption algorithm. The ciphertext may then be decoded (or decrypted) by the receiver and thereby turned back into plaintext. The encryption algorithm uses a key, which is a binary number that is typically from 40 to 128 bits in length. The greater the number of bits in the key, the more possible key combinations and the longer it would take to break the code. The data is encrypted, or “locked,” by combining the bits in the key mathematically with the data bits. At the receiving end, the key is used to “unlock” the code and restore the original data.
There are two cryptographic methods in general use. The first method uses a secret key that is used by both the sender and receiver to encrypt and decrypt the plaintext information. A drawback of this method is that it is hard for the sender to deliver the secret key to the receiver without risking its compromise. The second method is known as public-key cryptography, which uses two keys known as a private and a public key. Each party has a private key that is kept secret and not shared, and a public key that is made publicly available. The public key is used to encrypt the plaintext information, and the private key is used to decrypt the ciphertext message. The private key may not be mathematically derived from the public key. The parties to a communication may exchange their public keys over an unsecured communication channel, such as the Internet, and thereafter use the public keys to encrypt their messages. The receivers then use the private key to decrypt the message.
Another important consideration for a communication system is the prevention of unauthorized copying of copyright-protected digital content. With conventional computing and communication systems, an unscrupulous individual can easily make and distribute an unlimited number of identical copies of a copyrighted work in digital form (e.g., music, literary works, photography, video, software, etc.). Moreover, commercially available file indexing services allow computer users to easily locate and access digital files on other user's computer systems, thereby greatly increasing the potential for widespread copyright piracy. One such service provided by Napster, Inc., of San Mateo, Calif., provides a file sharing application that works in conjunction with Napster's Web site to locate music files in the popular MP3 format residing on other computers currently logged onto the Internet. A similar service known as Gnutella provides a file sharing system that allows users to search for software and documents on the GnutellaNet, a loose federation of users and organizations that make a wide variety of information available to the world at large. Gnutella differs from Napster, which is geared to music files and provides a centralized listing, whereas the GnutellaNet is a peer-to-peer network that contains all kinds of files. While these file sharing systems also have a legitimate purpose in enabling users to share non-copyright-protected files, they are also widely used to obtain copyright-protected files in violation of copyright laws. The illicit use of these file sharing systems represents a serious threat to copyright owners.
Active policing of the Internet is not a viable solution for copyright holders. Such policing efforts are logistically difficult given the widespread and anonymous nature of Internet copyright piracy. In addition, the popular sentiment that information content exchanged on the Internet should be free makes large scale policing efforts very unattractive from a public relations standpoint. To address this problem, various digital rights management (DRM) systems have emerged for protecting the copyrights of digital content that is distributed by focusing on preventative measures. For example, a proposed DRM system for the recording industry known as the Secure Digital Music Initiative (SDMI) sets forth a set of rules for securely distributing digital music over the Internet. SDMI provides guidelines for developing compliant DRM systems, including a container format that software and hardware players must support in order to play back the material. Announced in February 1999, the SDMI is backed by the Recording Industry Association of America (RIAA) and Sony, Warner, BMG, EMI and Universal, the top five music production companies.
Notwithstanding these efforts, DRM systems present at best an incomplete solution for a number of reasons. First, given the availability of pirated content on the Internet, it is far more convenient and inexpensive for a user to unlawfully download a digital file over the Internet than to purchase a legitimate copy of the material via conventional channels of trade. While the unlawfully obtained material may have reduced quality in comparison to the legitimate copy, the convenience and negligible cost often make up for this drawback.
Second, most DRM technologies rely upon some form of encryption to protect the digital information. To be most effective, both parties to an encryption scheme must have a vested interest in maintaining the secrecy of the encrypted information. A legal purchaser of content has a right to view the content, but has no vested interest in ensuring that the secrecy afforded by encryption is maintained. For this reason, many DRM solutions utilize digital certificates or licenses that attempt to hide the decryption key from the user. In such systems, all copies of the content are encrypted in an identical manner, and the media player validates the user's right to display or play back the decrypted content. Since the encrypted content and decryption key are nevertheless accessible to the user albeit hidden, a sophisticated user may reverse engineer the DRM solution to strip away the encryption to thereby permit unimpeded copying and distribution of the decrypted content. Other less sophisticated ways of obtaining an unencrypted copy of the content are also available to unscrupulous users, such as videotaping each frame of a digital video data file as that content is legally displayed during playback.
Accordingly, it would be very desirable to provide a way to control the interchange of digital information that overcomes these and other drawbacks. More particularly, it would be desirable to provide an information interchange system and method that allows control over security and access to the information, and which prevents unauthorized copying of copyright-protected content.